Microbiology Classification Systems
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Questions and Answers

What is the most common cause of UTIs?

  • E. coli (correct)
  • Mycobacterium
  • Serratia marcescens
  • Pseudomonas aeruginosa

    • What is the purpose of an acid-fast stain?

  • To detect lactose fermentation
  • To identify Mycobacterium tuberculosis (correct)
  • To detect Pseudomonas aeruginosa
  • To identify E. coli

    • What is the current classification scheme favored by most microbiologists?

  • Five-kingdom system
  • Two-kingdom system
  • Four-domain system
  • Three-domain system (correct)

    • What can be used to identify bacteria?

    <p>Colony morphology and metabolic capabilities</p> Signup and view all the answers

    What is the main difference between the five-kingdom system and the three-domain system?

    <p>The classification of prokaryotic organisms</p> Signup and view all the answers

    What is a characteristic of Pseudomonas aeruginosa?

    <p>Produces a soluble greenish pigment</p> Signup and view all the answers

    What is the name of the scientist who proposed the five-kingdom system?

    <p>R.H. Whittaker</p> Signup and view all the answers

    What is a characteristic of Serratia marcescens?

    <p>Produces a red pigment when incubated at 22°C</p> Signup and view all the answers

    What is a characteristic of E. coli?

    <p>Ferments lactose to form pink colonies</p> Signup and view all the answers

    Which domain includes single-celled eukaryotes?

    <p>Eukarya</p> Signup and view all the answers

    What is the name of the kingdom that includes plants in the five-kingdom system?

    <p>Plantae</p> Signup and view all the answers

    What is an example of a differential medium?

    <p>Both A and B</p> Signup and view all the answers

    What can be used to identify a microorganism?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is an example of a prokaryotic organism?

    <p>Methano- bacterium</p> Signup and view all the answers

    What is the main characteristic that distinguishes Bacteria from Archaea?

    <p>Genetic differences</p> Signup and view all the answers

    Which of the following is NOT one of the five kingdoms in the five-kingdom system?

    <p>Archaea</p> Signup and view all the answers

    What is the main limitation of the five-kingdom system?

    <p>It does not recognize the distinction between Bacteria and Archaea</p> Signup and view all the answers

    What is the main advantage of the three-domain system?

    <p>It recognizes the distinction between Bacteria and Archaea</p> Signup and view all the answers

    What is the purpose of adding hydrogen peroxide in the catalase test?

    <p>To detect the presence of catalase enzyme</p> Signup and view all the answers

    What is the byproduct of urea degradation in the urease test?

    <p>Carbon dioxide and ammonia</p> Signup and view all the answers

    What is the function of an inverted tube in sugar fermentation test?

    <p>To trap any gas produced</p> Signup and view all the answers

    What is the minimum incubation period required for most biochemical tests?

    <p>18 hours</p> Signup and view all the answers

    What is the purpose of a dichotomous key in bacterial identification?

    <p>To lead to the identification of an organism</p> Signup and view all the answers

    What is detected in the Voges-Proskauer test?

    <p>Acetoin, an intermediate of the fermentation pathway</p> Signup and view all the answers

    What is the purpose of a pH indicator in the urease test?

    <p>To measure the acidity of the sample</p> Signup and view all the answers

    Why is catalase test considered one of the easiest and fastest biochemical tests?

    <p>Because it is a simple and rapid test</p> Signup and view all the answers

    What happens to the pH when an organism ferments sugar?

    <p>It lowers</p> Signup and view all the answers

    What is the purpose of a Gram stain?

    <p>To distinguish between Gram-positive and Gram-negative bacteria</p> Signup and view all the answers

    What does the 'O157' in E. coli O157:H7 refer to?

    <p>The serotype of E. coli</p> Signup and view all the answers

    Why are biochemical tests usually inoculated at the same time?

    <p>To save time and resources</p> Signup and view all the answers

    What is the purpose of gel electrophoresis in RFLP analysis?

    <p>To separate the fragments of DNA</p> Signup and view all the answers

    What is the significance of identical RFLPs in isolates of the same species?

    <p>They may or may not be the same strain</p> Signup and view all the answers

    What is the purpose of the oxidase test?

    <p>To identify Pseudomonas aeruginosa</p> Signup and view all the answers

    What is the result of a positive catalase test?

    <p>The decomposition of hydrogen peroxide</p> Signup and view all the answers

    What is the purpose of PulseNet established by the CDC?

    <p>To track foodborne disease outbreaks</p> Signup and view all the answers

    What is the purpose of the urease test?

    <p>To detect the presence of urease</p> Signup and view all the answers

    What is the advantage of multilocus sequence typing (MLST) over RFLP analysis?

    <p>MLST is more practical than RFLP analysis</p> Signup and view all the answers

    What is the purpose of restriction enzymes in RFLP analysis?

    <p>To cut the DNA into fragments</p> Signup and view all the answers

    What is the result of a negative coagulase test?

    <p>The absence of coagulase</p> Signup and view all the answers

    What is the purpose of a dichotomous key?

    <p>To identify the cause of urinary tract infections</p> Signup and view all the answers

    What is the unit of measurement used to express the size of restriction fragments?

    <p>Kilobase pairs</p> Signup and view all the answers

    What is the purpose of ethidium bromide in RFLP analysis?

    <p>To stain the fragments</p> Signup and view all the answers

    Study Notes

    Classification Systems

    • The three-domain system is the most widely accepted classification system, dividing organisms into Bacteria, Archaea, and Eukarya.
    • The five-kingdom system, proposed by R.H. Whittaker in 1969, categorizes organisms into Plantae, Animalia, Fungi, Protista, and Prokaryotae.
    • The three-domain system recognizes the differences between prokaryotic and eukaryotic organisms.

    Characteristics of Microorganisms

    • Colony morphology can give initial clues to the identity of an organism.
    • Metabolic capabilities, such as sugar fermentation and end products, are used to identify microorganisms.
    • Biochemical tests, like the Voges-Proskauer test, detect specific enzymes and metabolic pathways.

    Biochemical Tests

    • The catalase test detects the presence of the enzyme catalase, which breaks down hydrogen peroxide.
    • The sugar fermentation test detects the production of acid and gas, resulting in a color change.
    • The urease test detects the presence of the enzyme urease, which breaks down urea to produce carbon dioxide and ammonia.

    Identification of Microorganisms

    • A dichotomous key is used to identify bacteria based on biochemical tests and other characteristics.
    • The Gram stain is used to differentiate between Gram-positive and Gram-negative bacteria.
    • The oxidase test detects the presence of the enzyme oxidase.
    • The coagulase test detects the presence of the enzyme coagulase.

    DNA-Based Identification

    • Restriction fragment length polymorphisms (RFLPs) are used to identify and track foodborne bacterial pathogens.
    • The CDC's PulseNet database catalogs RFLPs of certain foodborne bacterial pathogens.
    • Multilocus sequence typing (MLST) involves sequencing and comparing the DNA of different isolates to identify and track microorganisms.

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    Description

    Learn about the three-domain system and the five-kingdom system, and understand the characteristics of microorganisms. Explore the differences between prokaryotic and eukaryotic organisms.

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